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No.5 (1972/03) >

 
Title :圧力水の吹出しを伴う円柱キャビテーション
Title alternative :Cavitation Characteristics for circular Cylinder with Pressure Water Supply from on its Surface
Authors :真栄田, 義才
Authors alternative :Maeda, Gisai
Issue Date :Mar-1972
Abstract :This paper presents the cavitation characteristics for circular cylinder when pressure water is supplied from surface of the cylinder to main flow around it. I reported already the cavitation characteristics of hydro-foils with pressure water supply. But I couldnit get good results at that time, because cavitation on the foils developed more suddenly by the pressure water. The pressure water is led from a water pipe directly to the testing cylinder. The cylinder has fourteen small holes on its surface, and they are located at some angle ± θ from the stagnation point of upstream side on the circular cylinder surface. Seven holes are located at+θ, the others are at -θ. Pressure water is supplied through these holes to main flow. The angle θ are 70°, 90°, 110°, and 130°. Experimental results show as follows; 1. When θ equals 70° drag coefficients are much larger than one of no pressure water supply. Cavitation inception coefficient varies from 5.0 to 4.2 while relative volume of pressure water increases from μ = 7.02×10^-3 to 2.92×10^-2. These values are very large compared with 2.0 for no water supply. 2. When θ takes 90°. drag coefficents are also larger, but they are somewhat smaller than ones for 70°. The inception coefficient takes from 4.0 to 2.6, decreasing with increasing relative volume of supplied water which is changed the same range to the former. 3. Drag coefficients almost equal to one of no pressure water When θ takes110°. Coefficients of cavitation inception varies from 3.7 to 3.2 with changing supplied water volume. 4. When θ equals 130°, drag coefficients are much smaller than one of no water supply. The former is about a half of the later within the range of none cavitation. Cavitation inception coefficient takes from 2.5 to 3.5, but on this time, the value increases with supplied water volume. All of them, cavitation inception coefficients are larger than one of no water supply. But when θ equal 110°and 130°, cavitation scarcely develops within some ranges of cavitation coefficients. At 110°for θ, the limiting cavitation coefficient for no development of cavitation varies from 2.7 to 1.8, and it decreases with increasing supplied water volume. At 130°, it varies from 1.8 to 1.6. As previously described, cavitation inception coefficient for no pressure water supply is about 2.0, and cavitation develops gradually with decreasing cavitation coefficient. Then, if the pressure water is supplied at about 130° from stagnation point of upper stream side, a scale of cavitation development is smaller than one of no pressure water supply.
Type Local :紀要論文
ISSN :0387-429X
Publisher :琉球大学理工学部
URI :http://hdl.handle.net/20.500.12000/24415
Citation :琉球大学理工学部紀要. 工学篇 = Bulletin of Science & Engineering Division, University of the Ryukyus. Engineering no.5 p.37 -52
Appears in Collections:No.5 (1972/03)

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